// JavaScript Document
//下面用于图片上传预览功能  
function setImagePreview(avalue) {  
var docObj=document.getElementById("myfile");  
var button = document.getElementById("button");
button.style.display="none";  
var imgObjPreview=document.getElementById("localimg");  
if(docObj.files &&docObj.files[0])  
{  
//火狐下，直接设img属性  
imgObjPreview.style.display = 'block';  
imgObjPreview.style.width = '300px';  
imgObjPreview.style.height = '200px';   
//imgObjPreview.src = docObj.files[0].getAsDataURL();  
   
//火狐7以上版本不能用上面的getAsDataURL()方式获取，需要一下方式  
imgObjPreview.src = window.URL.createObjectURL(docObj.files[0]);  
}  
else  
{  
//IE下，使用滤镜  
docObj.select();  
var imgSrc = document.selection.createRange().text;  
var localImagId = document.getElementById("localimg");  
//必须设置初始大小  
localImagId.style.width = "200px";  
localImagId.style.height = "200px";  
//图片异常的捕捉，防止用户修改后缀来伪造图片  
try{  
localImagId.style.filter="progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";  
localImagId.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgSrc;  
}  
catch(e)  
{  
alert("您上传的图片格式不正确，请重新选择!");  
return false;  
}  
imgObjPreview.style.display = 'none';  
document.selection.empty();  
}  
return true;  
}